# File lib/rubygems/specification.rb, line 597
    def validate
      normalize
      if rubygems_version != RubyGemsVersion
        raise InvalidSpecificationException.new(%[
          Expected RubyGems Version #{RubyGemsVersion}, was #{rubygems_version}
        ].strip)
      end
      @@required_attributes.each do |symbol|
        unless self.send(symbol)
          raise InvalidSpecificationException.new("Missing value for attribute #{symbol}")
        end
      end 
      if require_paths.empty?
        raise InvalidSpecificationException.new("Gem spec needs to have at least one require_path")
      end
    end